Patent GB-541535-A (GB)
Title: Improvements relating to the generation and transmission of radio waves
IPC: H03C7/02
Filed: 1940-05-30
Abstract: 541,535. Generating high-frequency oscillations; spark-gaps. STANDARD TELEPHONES & CABLES. Ltd. May 30, 1940, Nos. 9470, 9471, (Convention dates, June 14, 1939), and 9472, (Convention date, June 20, 1939). [Classes 39 (i) and 40 (v)] A wave generation system comprises an electric discharge gap, a source of periodically selfquenched electromotive force connected in circuit therewith and of sufficient peak E.M.F. to break down the gap, the gap having electrodes to serve as radiating elements to determine the frequency of the waves produced by the discharge across the gap, and an electric wave reflecting system to reflect the waves generated in the gap. Fig. 1 shows a discharge gap 24, 25 energized by a selfquenching oscillator of the kind described in Specification 141,046, [Class 40 (v)], in which the principle frequency generated by valve 2 is determined by the linear conductors 9, 10 terminated by capacities 11, while the quenching frequency is determined by reactances 13, 14, and is fed to the grid of valve 2 through a circuit 18, 19 tuned to the principle frequency. The ouput is taken from condensers 20 and fed to the electrodes 24, 25 through coils 21 and smaller coils 22, 23 in electrical contact with electrodes 24, 25 consisting of platinum or tungsten on the end of quartz rods. The wavelength of the oscillations radiated depend on the dimensions of the gap which is adjustable and the coils 21-23 form a series resonant circuit preventing loss of the oscillations through the electrodes. The gap is situated at the centre of a spherical metal reflector 34 the directional properties of which are further improved by a lens 43 of wax. A blower 45 provides 'a blast of air or oxygen to remove ionisation products and for cooling. The abovearrangement provides a series of trains of microwaves occurring at the quenching frequency, the intervals allowing the electrode to cool thus preventing excessive ionisation. To make the radiation approach the form of a continuous wave arrangements are described for extracting part of the radiation and reintroducing it into the train of waves with a suitable time lag. In Fig. 8 the gap 101 is in a metal tube 102 having a piston 109 to reflect the energy in one direction to produce a double train of waves to the left which are deflected by reflectors 110 into side. chambers into pistons 114, 115, 116, so arranged as to cause at the left hand side of the tube a series of wave trains closely and uniformly spaced so as to resemble a continuous wave. In another arrangement, Fig. 10 (not shown), two spark gaps feed into branches of the same tube the gaps being energized alternately. In Fig. 9 the energy from E passes through channels F, G, H, T of different lengths to be recombined at K into suitable time lag. Fig. 14 shows an arrangement for modulating the radiation by means of a microphone 201. As shown the common part of the circuit of the space current supply 203 to the self quenching oscillator 204 and to a modulator 202 is provided with a speech frequency choke 205, use being made of the Heising constant current circuit as in Specification 133,366, [Class 40 (v)]. This causes modulation of the output from 204 and a corresponding effect is shown in the energy radiated from spark gap 227 in that the number of half cycles in each train of waves from oscillator 204 which is of sufficient amplitude to break down the gap depends on the modulation amplitude. Curves to demonstrate this are drawn, Figs. 12, 13 (not shown). The spark gap is situated at one end of a wave group energy redistributed 228 provided with a radiator 234 such as the flaring horn described in Specification 466,063.